In-band noise from EMG and other sources is an obstacle to the extraction of accurate, reliable, and repeatable information from ambulatory ECG recordings. This issue is prevalent in multiple applications where ambulatory monitoring is used including diagnosis and management of patients at risk of cardiac arrhythmias and preclinical and clinical evaluation of drug safety and effectiveness.
Ambulatory ECG monitoring devices often incorporate the ability to detect arrhythmic events and store the ECG strip containing the event for later communication to a computerized system for further review. ECG strips detected by the ambulatory monitoring device as containing an arrhythmia are communicated to a computerized system where the strips containing the events are subjected to further analysis and are evaluated to screen out inaccurate and erroneous information. Other ambulatory devices record the ECG continuously or at regular intervals, and the ECG is communicated to a computerized system where intervals are measured and events are detected. Whether the ECGs are analyzed within the ambulatory monitoring device, at a computerized system located in an office, laboratory, or center dedicated to ECG analysis, or a combination thereof, noise can render the ECGs uninterpretable or very difficult to interpret and cause analysis algorithms to produce large numbers of false positive events and errors in interval measurements, requiring manual over-read of the results. This increases labor costs and risks introducing human error, leading to inferior information. For preclinical and clinical drug safety studies, where intervals and arrhythmias are often documented during analysis, noise introduces variability that increases the sample size necessary to reach statistical significance and creates false positives and errors that require expensive manual over-read. These and other matters present challenges to ECG monitoring.